Fluid-actuated oscillators



Dec 13, 1966 H. P. CHABRIER ETAL 3,291,153

FLUID-ACTUATED OSCILLATORS Filed Dec. 10, 1965 5 Sheets-Sheet 1 Dec. 13, 1966 H. P. cHABRn-:R ETAI. 3,291,153

FLUID-ACTUATED OSCILLATORS 3 Sheets-Sheet 2 Filed Deo. 10, 1963 .J A... Q n... rs J NQ z A f f Dec- 13, l966 H. P. CHABRIER ETAL 3,291,153

FLUID-ACTUATED OSC ILLATORS Filed Deo. 10, 1965 vSheets-Sheet 5 A l l 0f 0: d: l E er 7 c )7l 7i 274 75 x 77 "7 78 s V if] x United States Patent Ofice 3,29Ll53 Patented Dec. I3, 1966 2 ciaims. (ci. la7-624.14)

The present invention relates to oscillator arrangements actuated by a liquid or `gas Linder pressure.

It is an object of this invention to provide a fluid-actu ated yoscillator of particularly single design which essentially consists of :at least one valve of the type disclosed in the U.S. Patent No. 3,242,946 patented October 11, 1965, in the name of the applicants, for: Fluid-actuated logical devices.

Such a valve is of the conventional general type comprising a hollow body provided with a supply inlet orifice in communication with a source of fiuid pressure, an outlet orifice adapted for connection to a point of use, a reference pressure orifice, and a control pressure inlet, valve means movable between la first position connecting the sup-ply inlet and outlet orifices, While disconnecting the outlet and reference pressure orifices and a second position connecting the reference pressure and outlet orifices, While disconnecting the supply inlet and outlet orifices.

According to the above mentioned patent this fluidactuated valve has the feature that said hollow body has a chamber therein, with first, second, third and fourth mutually `adjacent chamber portions having in the respective walls thereof the four respective orifices, at least two seatings and at least one spherical valve closing member in the chamber and adapted to seat lagainst the seatings for :closing the communication between the respective rst, second and third chamber portions.

This particular feature of the `said valve enables one to establish the communication either between the supply inlet and the outlet orifices, or between the outlet and the reference pressure orifices Iand t-o obtain the switching from one position to the other in a very simple way.

With the above mentioned object in view, the oscillator arrangement according tto this invention further includes motor ymeans of a remarkably simple design, responsive to fluid pressure from the control inlet orifice and operatively connected to said spherical valve cl-osing member to move the latter from the first to the second position upon a predetermined increase in pressure at the control inlet orifice, and time delay means connecting the outlet orifice to the control inlet orifice.

It is another object of the present invention to provide an oscillator arrangement which is remarkably stable at comparatively low operating frequencies and which, for that pur-pose, consists of `an odd number of at least three fluid actuated valves of the `general type defined hereinabove, the supply inlet orifice of each of said valves being connected to the control inlet orifice of the next sucessive valve, the outlet of the last valve being connected via time delay means to the control inlet of the first valve.

These and other objects and features of the invention will become clearly apparent from t-he following description.

In the accompanying drawing:

FG. l is a .block diagram of a particularly versatile oscillator arrangement embodying the present invention;

FIG. 2 shows Ian embodi-ment of a fiuidactuated valve adapted for use in the oscillator arrangement illustrated in FIG. l;

FIG. 3 illustrates, in one of its stable operating positions, another embodiment of a Valve Iadapted for use in the arrangement of FIG. l;

FIG. 4 illustrates the valve of FIG. 3 in the stable operating position other than the one of FIG. 3;

FIG. 5 is a block diagram of another oscillator arrangement according to the invention; :and

FIG. 6 illustrates a liquid-actuated oscillator arrangement according to this invention.

In FIG. l there is shown a fluid-actuated valve schematically illustrated as la rectangle l comprising a supply inlet A, a control inlet E, a reference pressure outlet O and an active loutlet S. This valve is built in such a way that the pressure PA of the fluid prevailing at the supply inlet A is transferred to the outlet S only when the control inlet E is not submitted to la pressure higher than a predetermined level.

ti-on.

The active outlet S of the valve l is connected to the control inlet by means of a line connected therein, preferably including means for delaying the fluid flow, such as a fiuid resistance rl, a valve lor duct capable of introducing a pressure drop, for instance, -or a liuid capacity C1, i.e. a buffer chamber.

The operation of the oscillator arrangement just described is as follows:

When the supply pressure A is established the fluid is discharged via S until the moment when the pressure wave issued from S, delayed by resistance (r) and capacity (C) reaches E with ra level high enough for causing the interruption of the circuit AS and the establishment of the circuit OS. The latter is maintained until the moment when the `pressure at E, issued from S, has been sufficiently decreased through discharge at O to stop the inhibition of the communication AS. As long as the supply A is maintained, a self-sustained oscillation is obtained.

Valve 1 ofthe arrangement of FIG. l will, for instance, be of the type which is illustrated in FIG. 2.

It com-prises two balls of obturation B1 and B2, if required separated iby a ball B3 adapted for transmitting pressures without obturating any seating, a hollow body 21 comprising the seats 22, 23, 24 and orifices A, S, O and E in communication with fiuid supply sources, not shown.

It is clear that a connection is established between either A and S, or between A and O, according to the pressure which is exerted at E on ball B2, and transmitted by ball B3 O B1.

As a modification, valve 1 of the arrangement of FIG. l could also be of the type illustrated in FIGS. 3 and 4.

In this embodiment there is 'only one ball B1 which is capable of obturating either seating 32 (in the position represented in FIG. 3) or seating 33 (in the position represented in FIG. 4). This ball is pushed by a rod 34 In other words, this valve performs the s=af funcp controlled by a flexible diaphragm 35 which is submitted to the pressure of the fiuid exerted at E.

The device, as well as that of FIG. 1, embodies the function FIG. illustrates an oscillator arrangement constituted by three valve units 51, 52 and 53 supplied in parallel, .the control inlet of each valve being connected to the active outlet of the preceding one, by means of a feedback loop c-omprisin-g a capacity C5 -and a fiuid resistance 1'5 being connected between the general outlet S of the arrangement and the inlet El of the first valve unit.

It should be observed that an oscillat-or arrangement of the type as illustrated in FIG. 5 comprises yan odd number of valve units: this is a condition for the signal .r3 at the outlet S3 to be the logical inverse of signal e1, which is applied to inlet E1. Besides, in order to obtain that the pressure .transferred `from S to E1 be sufficiently high to switch valve 51, in practice units 51, 52 and 53 should -be built so as to operate -as amplifiers. This will be obtained by properly dimensioning these units, as explained in the patent application already referred to. l

In comparison with the arrangement of FIG. 1, the one of FIG. 5 possesses the advantage of being more stable at comparatively low frequencies, not exceeding 1 Hertz, for instance, and of being more easy to adjust.

At frequencies not exceeding 0.1 Hertz it is a-dvantageous, lin view of obtaining a sharper turnover of the device, to connect in the feedback loop in series with capacity C5 a device as illustrated in mixed line, together with its circuit connections, and indicated by reference numeral 56, the function of which will be explained hereinafter.

This devi-ce will preferably consist of a bistable unit having a variable switching threshold level, either positive -or negative, per-forming the function of delivering at its outlet S6 a pressure having a rectangular waveform, said pressure being supplied from the common supply source A, as soon as the pressure at its inlet E6, issued from the pressure in S, exceeds a predetermined threshold level, this threshold level being as close Ias desired to the common supply pressure.

Such a bistable unit will for instance consist of a direct acting amplifying relay -as disclosed in the U.S. Patent No. 2,772,688, patented December 4, 1956, and illustrated in FIG. l of `the said patent, under reference numeral 14.

In case a negative threshold bistable unit is utilised means have to be provided for re-establishing the phase reversal between S and E1. These means will, for instance, consist of a valve unit as the one of FIG. 1.

It is also possible to obtain a sharp switching at comparatively low frequencies by connecting between S and El and even number of valve units supplied yfrom the common source, the inlet of one unit being connected to the outlet of the preceding one, these units having such characteristics that the unit closest to E1 switches when submitted to ya pressure very close .to the common supply pressure, without :any modifications in the phase difference between S and E1.

In this way the oscillation `frequency of the system is better defined.

As the filling of capacity 5 tfollows :an exponential law corresponding to a rate of increase which is the lower as the fiuid flow through resistance 5 is the lower, the fact that it is possible to adjust by means of device 56 the threshold of operation at any predetermined and accurately defined level 'and to obtain the starting of the signal `at S, and, consequently at E1, at a time which is accurately defined and as delayed as desired.

The -oscillat-or arrangement of FIG. 5 is :apt to provide at outlets S1, S2 land S3, als well pulsatory signals such as pressure signals Without any flow, as la pulsatory flow of the supply `fi-uid, this pulsatory fiow being delivered under pressure.

In the latter Icase .the arrangement behaves likes an adjustable pulsatory fiow pump, the flow being determined by the supply pressure `and by the delay due to the feedback loop 1'5, C5, 56.

The arrangement of FIGURE 5, as Well as the one of FIGURE l, may be equipped with valve units of one of the .two types respectively illustrated in FIGURES 1 and 3, or, more generally, of the general type which has been defined hereinabove.

FIGURE 6 illustrates an embodiment of liquid-actuated oscillator utilising for instance five valve units 71-75. These valve units are supplied in parallel from rotary pump 77, the inlet of each of them being connected to the outlet of the preceding one, and `a feedback loop comprising a capacity C7 and a fluid resistance f7, connecting inlet El, of the first unit to outlet S of .the whole arrangement.

Such an arrangement may be .utilised ras Aa periodic pressure oil generator. The oil flows `along a closed circuit lost at the discharge orifices O1 t-o O5 being recovered at the bottom of the casing 78 of the assembly.

The arrangement may also be used as an alternating volumetric pump, a gate 79 in that case controlling the -outlet flow and a charge tank 80 providing the oil supply.

It kshould be observed that oscillators according to this invention function correctly with both a compressible fluid, compressed air for instance, and with an incompressible fiuid. In case of an incompressible fluid, the capacities will preferably consist of a chamber having slightly elastic walls, such yas a bellows.

Without departing from the lscope and spirit of the invention, some of `the connections between valves other than the feedback loop between the outlet of the last one and t-he inlet of the first, may comprise fiuid capacit-ies or resistances. Also, some connections between the valve units may comprise devices which modify the .form or the amplit-u-de of the signal.

It may be necessary also to connect in the oscillating circuit some valve units, the presence of which in this circuit not modifying, however, the phase difference of the feed back pressure wave.

It is desired to recover the fluid that escapes via the orifices O, one .may assemble the latter by means of a collector or direct them towards a tank out of which the fluid can be recovered.

The labove description `and the drawings should be taken in an illustrative sense only and not in a limiting sense.

Of course there are modifications to this invention which will fall within the scope and spirit thereof, and which will be apparent t-o those skilled in the art.

What is claimed is:

1. A fluid actuated oscillator comprising an odd number of 'at least three successive actuated valve units, each valve unit consisting of a hollow body having at least four orifices, a first orifice being an inlet orifice adapted Ifor connection to a source of pressure, a second being an active outlet orifice adapted for connection to a point of use, a third being a `reference pressure outlet, and a fourth being a control pressure inlet, valve means movable between -a first position connecting the first and second orifices while disconnecting the second and third orifices and a second position connecting the second and third orifices While disconnecting the first and second orifices, motor means responsive to 4fiuid pressure from the control inlet orifice and operatively connected to the valve means to move the latter from the `first to the second position upon a predetermined increase in pressure at the control inlet orifice, the inlet orifice of each unit being connected to a common source of fiuid pressure, the active outlet of each unit except the last being connected tQ the @OUH O1 inlet orifice of the next successive unit, the

5 active outlet `of the last unit being connected via time delay means to the control inlet of the rst unit.

2. A fluid actuated oscillator `as claimed in claim 1, wherein said time delay means include a Huid resistance, a Huid `capacitance and a bistable device having a predetermined uid pressure switching threshold level.

References Cited by the Examiner UNITED STATES PATENTS Gray 137-625.66 X Whalen 251-62 X Spence 137-485 `Greef 137-102 Brock 137-102 Lucien 137-625.27 X Wiegand 60-52 Etter 137-815 X Riordan 137-624.14 X

ALAN COI-IAN, Primary Examiner. 

1. A FLUID ACTUATED OSCILLATOR COMPRISING AN ODD NUMBER OF AT LEAST THREE SUCCESSIVE ACTUATED VALVE UNITS, EACH VALVE UNIT CONSISTING OF A HOLLOW BODY HAVING AT LEAST FOUR ORIFICES, A FIRST ORIFICE BEING AN INLET ORIFICE ADAPTED FOR CONNECTION TO A SOURCE OF PRESSURE, A SECOND BEING AN ACTIVE OUTLET ORIFICE ADAPTED FOR CONNECTION TO A POINT OF USE, A THIRD BEING A REFERENCE PRESSURE OUTLET, AND A FOURTH BEING A CONTROL PRESSURE INLET, VALVE MEANS MOVABLE BETWEEN A FIRST POSITION CONNECTING THE FIRST AND SECOND ORIFICES WHILE DISCONNECTING THE SECOND AND THIRD ORIFICES AND A SECOND POSITION CONNECTING THE SECOND AND THIRD ORIFICES WHILE DISCONNECTING THE FIRST AND SECOND ORIFICES, MOTOR MEANS RESPONSIVE TO FLUID PRESSURE FROM THE CONTROL INLET ORIFICE AND OPERATIVELY CONNECTED TO THE VALVE MEANS TO MOVE THE LATTER FROM THE FIRST TO THE SECOND POSITION UPON A PREDETERMINED INCREASE IN PRESSURE AT THE CONTROL INLET ORIFICE, THE INLET ORIFICE OF EACH UNIT BEING CONNECTED TO A COMMON SOURCE OF FLUID PRESSURE, THE ACTIVE OUTLET OF EACH UNIT EXCEPT THE LAST BEING CONNECTED TO THE CONTROL INLET ORIFICE OF THE NEXT SUCCESSIVE UNIT, THE ACTIVE OUTLET OF THE LAST UNIT BEING CONNECTED VIA TIME DELAY MEANS TO THE CONTROL INLET OF THE FIRST UNIT. 